Rutheniridosmine is a naturally occurring mineral alloy of the elements ruthenium, iridium and osmium with the formula of . Rutheniridosmine occurs as hexagonal, opaque, silver-white, metallic grains with a Mohs hardness of six. Platinum, palladium, rhodium, iron, and nickel occur as impurities.[1]
Rutheniridosmine occurs in association with sperrylite, hollingworthite, iridarsenite, ruthenarsenite, michenerite, laurite, geversite, moncheite, and chromite.[2]
Type localities include: the Ruby Creek, Spruce Creek, and Bullion mines of British Columbia, Canada and the Horokanai placer deposit, of Kamikawa Subprefecture, HokkaidÅ, Japan.[1]